I buy old wreaths in garage sales to reuse. I take them home, strip all the old stuff off and swish them for a minute in a bathtub of lukewarm water with a dab of hair conditioner mixed in. Hang them outside to dry, and they come out looking brand new!! I once tried to dry one in a hurry with a blow dryer, and it didn't look too good :^(

:) you can clean them just like wicker- I like to use a drop or two of murphy's oil soap in the water instead of the conditioner, though that's not a bad idea :)!
and it 'scrub' them with an old paint brush to get the dust loose.

then air dry them flat in the shade- an old screen propped up like a sweater drying rack is ideal.